The present invention relates broadly to aggregate particle shields, known as wearliners, for aggregate material transport devices such as line vibratory feeders, discharge chutes, feeder hoppers, and the like, and more particularly to an aggregate particle shield having an array of ceramic cylinders upstanding in a molded bed, presenting a surface for impact by aggregate particles. Wearliners are known generally throughout the ore production industry as well as that segment of the power generation industry utilizing coal-fired power plants. Ore in its aggregate form must be transported from the mine to the power plant (or wherever it is used) and much of the transport is along conveyors, down chutes, through hoppers, and along vibrating feeders. Also, ore is often sifted to remove contaminants using a vibratory screen.
The ore particles themselves are highly abrasive, being formed of an extremely hard material and appearing in highly irregular shapes. As such, the areas surrounding transport devices tend to take a heavy beating from the loose ore set into motion by the transport device itself.
To protect the equipment involved, an aggregate particle shield is utilized. Positioned on surfaces which receive aggregate particle input, a typical aggregate particle shield must present a highly abrasive resistent surface for impact with the aggregate ore (or whatever abrasive aggregate substance is involved) in a manner light and flexible enough to adapt to various locations and applications.
One current aggregate particle shield utilizes rows of ceramic plugs upstanding in a bed of hardened polyurethane with only the upper surface of the plug initially exposed for impact. Aggregate particle shields are generally relatively thin in relation to their length and width dimensions in order to take up as little space as possible along the transport device or within the vibratory feeder box while still presenting a large area for impact. As such, the impact force must be absorbed by a small wear-resistant body, the impact plug. Accordingly, it is desirable to maximize the surface area of ceramic material exposed to impact.
The impact plugs are arranged in regular rows and columns and are held in place by the polyurethane. The plugs themselves are formed of a highly wear resistant ceramic material and each has a large hole bored through the plug body. During molding, this hole fills with polyurethane, and when filled, helps to anchor the ceramic plugs in place within the polyurethane bed. Since the plugs are arranged in a strict row and column arrangement, smaller diameter plugs of a like material are used to fill part of the space between the plugs.
One significant problem encountered with current aggregate particle shields occurs when plugs loosen within the polyurethane after repeated impact. While the ceramic plugs themselves can generally absorb such repeated impact for years, they may become dislodged from the polyurethane and eventually fall out of the shield. Further, the large diameter hole required to be drilled through the plug body, although filled with polyurethane when in use, weakens the structural integrity of the plug resulting in more frequent plug fracture. Another problem which arises is chipping along the edges of the plug due to the sharp edge between the upper flat impact surface and the annular side wall of the plug body. Impact forces along this sharp edge are absorbed by a very small surface area which can cause chipping. Further, the smaller plugs that are used to fill the space between the rows and columns of larger plugs fracture and chip much more easily than the larger plugs due to their small size.
It is accordingly an object of the present invention to provide an aggregate particle shield utilizing only one size of plug which is less resistant to fracture, maximizes the ceramic impact surface presented for aggregate particle impact, and in which the plugs are more firmly held in place.